Method for producing an electrical connection of a vehicle contact unit, vehicle connection device, and vehicle

ABSTRACT

A method for establishing an electrical connection of a vehicle contact unit of a vehicle which is at least in part electrically powered, to a ground contact unit of an electric charging infrastructure is provided. The ground contact unit has a plurality of electrical contact surfaces, at least two of which have to be contacted by the vehicle contact unit for charging the vehicle battery. The method includes the step of detecting, with the aid of at least one camera on the vehicle, at least one of the electrical contact surfaces and/or at least one insulation surface surrounding the electrical contact surfaces, for establishing an electrical connection. Further provided are a vehicle connection device for electrically connecting a vehicle contact unit of a vehicle which is at least in part electrically powered, to a ground contact unit of an electric charging infrastructure, and a vehicle having a vehicle connection device.

FIELD OF THE INVENTION

The disclosure relates to a method for establishing an electricalconnection of a vehicle contact unit of a vehicle which is at least inpart electrically powered, to a ground contact unit of an electriccharging infrastructure. The disclosure further relates to a vehicleconnection device for electrically connecting a vehicle contact unit,and a vehicle having such a vehicle connection device.

BACKGROUND OF THE INVENTION

In electrically powered vehicles, such as plug-in hybrid vehicles andpure electric vehicles, the batteries of the vehicles have to be chargedregularly, preferably after each trip. For this purpose, the vehicle isconnected to the charging infrastructure by means of a vehicleconnection system.

For example, vehicle connection systems with a contact unit of thecharging infrastructure that is provided on the ground are known. Thisground contact unit, arranged on the ground, is physically contacted bymeans of a displaceable vehicle contact unit, which can move downwardsfrom the underbody of the vehicle. This allows the vehicle to beelectrically connected to the charging infrastructure.

These vehicle connection systems require a physical contact between theelectrodes of the vehicle contact unit and the contact surfaces of theground contact unit. In these systems, problems occur due to the vehiclecontact unit not resting correctly on the contact surfaces of the groundcontact unit, for example because of soiled, covered or damaged contactsurfaces and, as a result of this, a charge transfer between thecharging infrastructure and the vehicle cannot be effected or cannot beeffected efficiently.

SUMMARY OF THE INVENTION

Thus, there is a need to provide a method and a vehicle connectiondevice which can provide an electrical connection of the contact unitarranged at the vehicle to a contact unit, arranged on the ground, ofthe charging infrastructure with high quality and low losses. A furtherneed is to provide a vehicle having such a vehicle connection device.

For this purpose, a method for establishing an electrical connection ofa vehicle contact unit of a vehicle which is at least in partelectrically powered and has a vehicle battery, to a ground contact unitof an electric charging infrastructure is provided. The charginginfrastructure includes a plurality of electrical contact surfaces, atleast two of which have to be contacted by the vehicle contact unit forcharging the vehicle battery. The method comprises the step ofdetecting, with the aid of at least one camera on the vehicle, at leastone of the electrical contact surfaces and/or at least one insulationsurface surrounding the electrical contact surfaces, for establishing anelectrical connection. In this way, the electrical contact surfaces andtheir positions are detected directly or indirectly via the surroundinginsulation surface. This means that the electrical contact surfaces canbe approached in a targeted manner, as a result of which an electricalconnection of the vehicle contact unit to the ground contact unit can beensured with high quality and low losses.

Within the scope of this disclosure, a camera is understood to mean anyoptical detection means, such as, e.g., a CCD camera, an array ofphotodiodes or the like.

Alternatively, the electrical contact surfaces may also be detectedindirectly by detecting markings that are provided at close range(approx. 2-5 m away) of a respective ground contact unit and allowconclusions to be drawn about the positions of the electrical contactsurfaces of the ground contact unit. In this way, the ground contactunit can be detected even if it is completely covered by leaves, forexample.

The method may additionally comprise the step of determining, with theaid of at least one camera on the vehicle, which electrical contactsurfaces of the ground contact unit are suitable for the electricalconnection. In this context, an electrical contact surface is consideredto be suitable for the electrical connection if it is either exposed,i.e. not covered and in particular not soiled, or if it is only slightlysoiled so that when it is contacted, an electrical connection can beestablished with no or only low power losses. In particular, anelectrical contact surface is furthermore only considered to be suitablefor the electrical connection if it does not exhibit any mechanicaldamage that significantly impairs the electrical connection. If thevehicle and/or the vehicle contact unit includes a cleaning device or acleaning function, even a more heavily soiled or even completely coveredelectrical contact surface may be considered suitable for the electricalconnection. Examples of removable soiling or objects that may coverelectrical contact surfaces include liquids, in particular water or oil,salt crusts, pollen, tire wear particles, brake dust, loose chippings,leaves and paper. In order to determine which electrical contactsurfaces of the ground contact unit are suitable for the electricalconnection, in particular the image data of the camera can be comparedwith one or more reference images. Furthermore, it is not necessary forall electrical contact surfaces of the ground contact unit to be withinthe field of view of the camera. It may also be sufficient to observeonly a portion of the ground contact unit. In this step, it is thusdetermined which electrical contact surfaces of the ground contact unitare, in principle, suitable for the electrical connection due to theirposition, arrangement and/or quality or nature, and which are not.

In step b) of the method, it may further be determined, with the aid ofthe at least one camera on the vehicle, which contact surfaces areexposed for the electrical connection and/or whether a soiling of theground contact unit is opposed to a safe charging process. An electricalcontact surface here is considered to be exposed for the electricalconnection if it is not covered and in particular not soiled or onlyslightly soiled, so that when it is contacted, an electrical connectioncan be established that involves no or only low power losses.

In addition, certain kinds of soiling may oppose a safe chargingprocess. If a charging process were to be carried out in spite of thissoiling, such soiling would result in that only a poor or eveninsufficient electrical contact may be achieved between the soiledcontact surface and the corresponding electrode and/or that the soiling,e.g. a puddle of water, electrically connects two contact surfaces witheach other, so that creeping currents are produced between the contactsurfaces concerned or even a short circuit occurs, preventing safecharging.

In order to determine which electrical contact surfaces of the groundcontact unit are exposed for the electrical connection, here too inparticular the image data of the at least one camera can be comparedwith one or more reference images. In this way, the electrical contactsurfaces are identified which are directly available for an electricalconnection with high quality and low losses.

Additionally or alternatively, in step b) of the method it may bedetermined, with the aid of the at least one camera on the vehicle,which electrical contact surfaces for the electrical connection are notexposed and show a soiling which, in particular, is cleanable. This alsoincludes electrical contact surfaces which cannot be directly detectedby the at least one camera, for example because they are completelycovered by a leaf. The type of soiling that is considered cleanablebasically depends on the cleaning device or cleaning function of thevehicle and/or the vehicle contact unit.

Soiling is considered to be non-cleanable if, for example due to itsmass, consistency and/or adhesive properties, it cannot, or notefficiently, be removed by the cleaning device or the cleaning functionof the vehicle and/or of the vehicle contact unit.

This in particular includes objects having a mass of more than 10 g,such as larger stones, as well as chewing gum and droppings. Mechanicaldamage to the electrical contact surfaces that significantly impairs theelectrical connection may also count as non-removable soiling. In thisway, the electrical contact surfaces are determined which are inprinciple available for an electrical connection, but require priorcleaning.

According to an alternative embodiment, the method includes the step ofselecting an area of the ground contact unit that is to be headed forelectrical connection, the area including a group of exposed contactsurfaces by means of which the electrical connection can be established.The group particularly corresponds exactly to the number of electricalcontact surfaces in exactly the arrangement required to establish anelectrical connection. Preferably, the area consists of the group. Thisensures a reliable electrical connection with high quality.

The method may further include the step of selecting an area of theground contact unit that is to be headed for electrical connection, thearea including at least one contact surface which is not exposed forestablishing an electrical connection. In particular, the areacorresponds exactly to the number of electrical contact surfaces inexactly the arrangement required to establish an electrical connection.When making the selection, exclusively those electrical contact surfacesare considered which are suitable and are exposed or consideredcleanable. This means that severely damaged or heavily soiled electricalcontact surfaces are not part of the area of the ground contact unitthat is to be approached for electrical connection. Therefore, areaswith soiled but cleanable electrical contact surfaces can also beutilized for establishing an electrical connection, as a result of whichit is not only easier and faster to establish the electrical connection,but it is also possible to use ground contact units for establishing anelectrical connection which would otherwise not be usable because theydo not exhibit an appropriate group of exposed contact surfaces by meansof which an electrical connection can be established.

After selecting the area, it may be provided that the vehicle contactunit is moved downward against the ground contact unit to establish theelectrical connection. In doing so, the electrical connection isestablished in particular in the selected area so that an electricalconnection with high quality and low losses is ensured.

In an alternative embodiment, the method includes performing a fullyautomatic cleaning step. In particular, step b) is performed subsequentto the cleaning step in order to determine again which electricalcontact surfaces are suitable for the electrical connection after thecleaning. The cleaning process allows soiling to be removed andelectrical contact surfaces to be exposed, which are then available forestablishing an electrical connection. Provision may be made for aplurality of cleaning steps, in particular if cleaning has not beensuccessful, for example in the case of heavy soiling, which requires agreater cleaning effort.

Provision may further be made that after selecting the area, the vehicleis moved, steering automatically, or optical steering signals are outputin the interior for the driver for manual steering of the vehicle inorder to place the vehicle contact unit in a position in which it can becoupled to the selected contact surfaces. In this way, the maneuver ofthe vehicle required for coupling can be facilitated or taken over forthe driver, whereby comfort is increased and a safe establishment of theelectrical connection between the vehicle contact unit and the groundcontact unit can be ensured.

For performing step a) and/or step b), an underbody camera and/or afront camera and/or a rear camera of the vehicle may be used. Theunderbody camera has the advantage that the ground contact unit and/orthe electrical contact surfaces can be detected even when the vehicle islocated above the ground contact unit.

Provision may further be made for a specific number of electricalcontact surfaces, in particular in the selected area, to be electricallyconnected only after the electrical connection has been establishedbetween the vehicle contact unit and the ground contact unit.Preferably, only those electrical contact surfaces are connected herewhich are required for the charge transfer.

For this purpose, according to the disclosure a vehicle connectiondevice for electrically connecting a vehicle contact unit of a vehiclewhich is at least in part electrically powered and has a vehiclebattery, to a ground contact unit of an electric charging infrastructureis also provided. The ground contact unit has a plurality of electricalcontact surfaces, at least two of which have to be contacted by thevehicle contact unit for charging the vehicle battery. The vehicleconnection device includes the vehicle contact unit, at least one cameraand a controller coupled to the camera. Furthermore, the vehicleconnection device is particularly configured to carry out the methodaccording to the disclosure. The controller is configured such that itcan determine exposed electrical contact surfaces of the ground contactunit by means of the at least one camera. This may be effected, forexample, in that the image data of the camera are compared with one ormore reference images. This allows exposed contact surfaces to bespecifically approached for the electrical connection of the vehiclecontact unit to the ground contact unit and an electrical connectionwith high quality and low losses to be provided when the vehicle batteryis charged.

The vehicle connection device may comprise a cleaning device which isprovided for exposing and/or cleaning the electrical contact surfaces ofthe ground contact unit at least in the selected area. The selected areais the area that is intended for electrical connection of the vehiclecontact unit to the ground contact unit. Electrical contact surfaces canbe cleaned and/or exposed by means of the cleaning device by removingsoiling and/or foreign bodies. This allows the quality of the electricalconnection to be improved and thus power losses to be reduced.

According to one embodiment, the controller for a positioning aid, bymeans of which the vehicle can be positioned, steering automatically,relative to a ground contact unit of an electric charginginfrastructure, is configured such that it can detect visual features onthe ground contact unit which are stored as a reference in thecontroller. Additionally or alternatively, visual features can bedetected which are provided in the close range, i.e. up to 3 m away fromthe ground contact unit, for example on the parking space or the parkingspace boundary of the ground contact unit. These features, which are forexample markings or codes, are intended for orientation and facilitatenavigation and the detection of the ground contact unit and/or theelectrical contact surfaces.

To this end, the electrical contact surfaces of the ground contact unitmay constitute a visual feature for the positioning aid, for examplebased on their arrangement, their shape and/or markings provideddirectly on the electrical contact surfaces, such as notches. Since theelectrical contact surfaces are usually made of a resistant metallicmaterial, the feature can be provided permanently in this way.

Alternatively or in addition, the visual feature may also include areflection and/or the intensity of the reflection of the light from alighting device of the vehicle contact unit at the contact surfaces. Forexample, the contact surfaces can be identified based on their strongerreflection in comparison with the reflection of the insulation surface.

The subject matter of the disclosure further is a vehicle including avehicle connection device for electrically connecting a vehicle contactunit of a vehicle which is at least in part electrically powered, to aground contact unit of an electric charging infrastructure. Here, thevehicle connection device is in particular a vehicle connection deviceaccording to the disclosure. The vehicle further includes an underbodycamera for optically detecting the ground contact unit. The underbodycamera is a camera which views the ground under the vehicle and, inparticular, is arranged on the underside of the vehicle. Preferably, thevehicle contact unit is also within the field of view of the underbodycamera, particularly in the extended state of the vehicle contact unit.It is further possible to monitor the ground contact unit duringcharging, for example in order to initiate a protective reaction when ananimal walks on the ground contact unit and/or touches or moves thevehicle contact unit. A protective reaction may, for example, consist inemitting an acoustic signal to drive the animal away, or in reducing orturning off the voltage of the electrical contact surfaces. In this way,the electrical contacts can be approached more precisely and safety canbe increased. If the vehicle and/or the vehicle contact unit includes acleaning device or cleaning function, the underbody camera can furtherdetermine the result of a cleaning step without the vehicle having to bemoved for this purpose.

In an alternative embodiment, the vehicle includes a protective meanswhich covers the lens of the underbody camera, in particular to protectit from soiling and/or damage. The protective means is configured andcontrolled such that it uncovers the lens when a procedure ofelectrically connecting the vehicle contact unit to a ground contactunit of an electric charging infrastructure is initiated. After theconnection has been established or after the charging process has beencompleted, the lens is covered again. This protects the lens and thecamera during the time when it is not in use, thus avoiding functionalerrors such as incorrect detection of exposed electrical contactsurfaces due to a soiled or scratched lens.

The vehicle may further include a lighting device that is provided toilluminate the image-taking area of the underbody camera in order toimprove the quality of the image data and thus the detection capability.In particular, the lighting device is adapted to provide light in aspecial wavelength range such as UV, which allows appropriately designedmarkings to be particularly easily detected, and can thus additionallyimprove the capabilities of detecting the marking or determining theelectrical contact surfaces. The lighting device includes, for example,one or more LEDs.

According to a further embodiment, the vehicle may have an electroniccontroller for autonomous steering. In addition or alternatively, thecontroller may provide a positioning aid, by means of which the vehiclecan be positioned, steering automatically, relative to a ground contactunit of an electric charging infrastructure. Furthermore, the controllermay additionally or alternatively be connected to a visual directionindicator in the vehicle interior, which can indicate to where thedriver is to steer the vehicle, so that an electrical connection of avehicle contact unit of the vehicle to the ground contact unit can beestablished. If the vehicle connection device includes a controller,this controller may be identical to the controller of the vehicleconnection device. In this way, the driver can be assisted by thecontroller during a coupling maneuver, or the controller independentlytakes over the maneuvering of the vehicle to establish an electricalconnection. This increases the comfort for the driver and ensures thatthe electrical connection between the vehicle contact unit and theground contact unit can be established correctly.

To provide a more accurate positioning aid, further sensors orfacilities such as GPS, WLAN, ultrasound or NFC may be provided.Furthermore, the steering angle and the wheel speed of one or morewheels of the vehicle may be taken into account for the positioning aid.

It is also conceivable that at least one coil and/or at least one radiotransmitter is/are arranged at at least one predetermined point in theground contact unit and the vehicle contact unit includes acorresponding receiver for electromagnetic signals and/or radio signals.Using the signals that are received by the receiver and were generatedby the coil and/or the radio transmitter, the position of the vehiclecontact unit relative to the ground contact unit can be determined, forexample by means of triangulation.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the disclosure will be apparent fromthe description below and from the accompanying drawings, to whichreference is made and in which:

FIG. 1 schematically shows a vehicle according to the disclosure with avehicle connection device according to the disclosure;

FIG. 2 shows a greatly simplified and schematic sectional view of thevehicle contact unit of the vehicle connection device according to FIG.1;

FIGS. 3a and 3b show sectional views of the vehicle contact unit in theregion of an electrode in various embodiments for resiliently mountingthe electrode;

FIG. 3c shows an enlarged view of a single electrode with a slidingactuator;

FIGS. 4a and 4b show greatly simplified schematic sectional views of thevehicle connection device according to FIG. 1 in a longitudinal and across section, respectively;

FIGS. 5a to 5c show various steps during the production of theelectrical connection between the vehicle contact unit and a groundcontact unit;

FIG. 6 shows, in a schematic illustration, further installations of thevehicle of FIG. 1;

FIG. 7 shows a perspective view of a ground contact unit with variouskinds of soiling;

FIG. 8 shows a top view of a ground contact unit with various visualfeatures for orientation; and

FIG. 9 shows a top view of a parking space with various visual featuresfor orientation.

DETAILED DESCRIPTION OF THE INVENTION

Lists having a plurality of alternatives connected by “and/or”, forexample “A, B and/or C” are to be understood to disclose an arbitrarycombination of the alternatives, i.e. the lists are to be read as “Aand/or B and/or C”. The same holds true for listings with more than twoitems.

FIG. 1 illustrates a vehicle 10, for example a battery-powered vehicleor a plug-in hybrid vehicle, parked on or above a ground contact unit 12having contact surfaces 13 of an electric charging infrastructure (notshown).

The electric charging infrastructure serves to recharge the batteries ofthe vehicle 10, in particular after a trip.

The underbody of the vehicle 10 has a vehicle connection device 14fastened to it, which can electrically connect the vehicle 10 to thecharging infrastructure, more precisely, which can electrically connecta vehicle contact unit 16 to the ground contact unit 12.

Besides the vehicle contact unit 16, the vehicle connection device 14includes a contacting actuator 18 and a sliding actuator 20 (FIG. 3c ).

The contacting actuator 18 may comprise a bellows 22 having an interiorspace 24 and a basic section 26, and a compressed air source 27, such asa compressor 28. A heating coil 29 that heats the air in the interiorspace 24 of the bellows 22 may further be provided in the interior space24 of the bellows 22 or in an air supply duct to the bellows 22.

The compressed air source 27 is in fluid communication with the interiorspace 24, so that the compressed air source 27 can inflate the bellows22.

A vehicle-side first end of the bellows 22 is fastened to the vehicle10, in particular to the underbody of the vehicle, by means of the basicsection 26. The vehicle contact unit 16 is fastened to the second end ofthe bellows 22 facing away from the vehicle 10.

The vehicle contact unit 16 is illustrated in FIG. 2 and includes a base30, for example in the form of a plate, in particular a circular plate,which closes the second end of the bellows 22. The plate is particularlymade from a plastic material.

On the front side of the base 30 facing away from the vehicle 10, thatis, the side of the base 30 facing the ground contact unit 12, the base30 has a contacting area 32 in which at least two electrodes 34 arearranged.

Further provided in the base 30 is an air outlet 36 which, on the onehand, is supplied from the interior space 24 and, on the other hand,opens into the contacting area 32. The air outlet 36 may also beconfigured as an air nozzle.

For example, the air outlet 36 opens out between two electrodes 34 andin the center of the base 30, i.e. centrally and in the region of thecenter of the contacting area 32. As a result, the air outlet 36 isdirected into a region in front of the contacting area 32, that is, intoa region between the base 30 and the ground contact unit 12.

The air outlet 36 is connected to the interior space 24 by means of acontrollable valve 38, which may be in the form of a throttle, so thatair from the interior space 24 can be blown out of the air outlet 36 ifrequired.

In addition, the base 30 includes a sealing lip 40, which is provided onthe outer circumference of the base 30 and completely encircles the base30 and the contacting area 32.

As can be seen in FIG. 3a , the electrodes 34 in the base 30 are eachspring-mounted in a respective cavity 41 of the base 30.

The electrodes 34 are configured as pins and each include a contact tip42, a base body 44 and a shoulder 46, which is arranged between the basebody 44 and the contact tip 42.

The shoulder 46 and portions of the base body 44 are arranged within thecavity 41, whereas the contact tip 42 extends from the cavity 41 in thecontacting area 32 and projects in relation to the front side of thebase 30.

Also provided in the cavity 41 is a spring 50, which rests, on the onehand, against the wall of the cavity 41 facing away from the contactingarea 32 and, on the other hand, against the shoulder 46.

The spring 50 is a compression spring so that it exerts a force on theshoulder 46 and thus on the entire electrode 34 towards the contactingarea 32.

It is also conceivable, as illustrated in FIG. 3b , that the spring 50is a leaf spring which acts on the end of the base body 44 facing awayfrom the contact tip 42.

FIG. 3c shows the sliding actuator 20 of the first embodiment, which isprovided on each of the electrodes 34. The sliding actuator 20 includesthree magnets. Two of the three magnets are electromagnets 52, i.e.switchable, and are arranged in the base 30 at the respective electrode34 on opposite sides of the electrode 34.

The third magnet is a permanent magnet 54, which is provided in theelectrode 34 such that it is positioned between the two electromagnets52.

Now if the two electromagnets 52 are operated such that they haveopposite polarities, the permanent magnet 54 inside the electrode 34 isattracted by one of the electromagnets 52 and repelled by the other.This causes the electrode 34 to move laterally, i.e. transversely to itslongitudinal extent, in a sliding direction R_(S).

Then when the polarities of the electromagnets 52 are reversed, theelectrode 34 is moved in the opposite direction. This allows theelectrode 34 to be reciprocated laterally by a quick changeover of theelectromagnets 52.

FIG. 4 illustrates a guide device 56 of the contacting actuator 18,which is not shown in FIG. 1 for reasons of clarity. On the other hand,FIG. 4 does not illustrate the air outlet 36 and the compressor 28. Theguide device 56 includes a restoring drive 58 and tension elements 60.

The restoring drive 58 has a spindle 59 which is mounted for rotation inrelation to the vehicle 10, tension elements 60 and a spiral spring 61.

One end of the spiral spring 61 is fastened to the spindle 59 and itsother end is fixed to the vehicle 10 so that the spiral spring 61 canapply a torque to the spindle 59.

It is also conceivable that instead of or in addition to the spiralspring 61, an electric motor drive 61′, such as an electric motor, isprovided for rotating the spindle 59. FIG. 4a illustrates, in dashedlines, such an electric motor drive 61′ in the form of an electricmotor.

The tension elements 60 may be bands, cords or ropes, and are alsoattached by one end to the spindle 59, so that the tension elements 60are rolled up on the spindle 59 when the spindle 59 is rotated.

The other end of each of the tension elements 60 is connected to thebase 30 at a connection point 62.

As can be seen in FIG. 4b , in the embodiment shown, three tensionelements 60 are provided, which are each connected to the base 30 at arespective connection point 62.

The connection points 62 are arranged in an equilateral triangle, thecenter of which is at the same time the center of the base 30.

The tension elements 60 run from the connection points 62 in theinterior space 24 of the bellows 22 vertically from the base 30 towardsthe basic section 26. The tension elements 60 are deflected by means ofdeflection pulleys 64, which may be provided in the interior space 24,and are then guided towards the spindle 59.

Here, the length of the tension elements 60 is selected such that thethree connection points 62 and thus the base 30 are always orientedhorizontally. In this way, the base 30 is always parallel to the groundcontact unit 12.

For locking the vehicle contact unit 16 in its retracted position, afirst locking element 66 and a second locking element 68 are furtherprovided in the middle of the base 30 in the interior space 24 and onthe opposite side at the basic section 26, respectively, the lockingelements being configured as latching hooks in the first embodimentshown.

The second locking element 68, i.e. the latching hook at the basicsection 26, is swivel-mounted here and can be swiveled from its verticalposition.

FIGS. 5a to c illustrate various steps during the contacting of thevehicle contact unit 16 with the ground contact unit 12.

The vehicle contact unit 16 can be moved towards and away from theground contact unit 12 with the aid of the contacting actuator 18. Here,the direction of movement is perpendicular to the ground contact unit 12and perpendicular to the contacting area 32 and will be referred to asthe contacting direction R_(K) below.

It is, of course, also conceivable that the vehicle contact unit 16 isnot only moved in the contacting direction R_(K) by the contactingactuator 18, but that when the vehicle contact unit 16 is lowered, amovement component in some other direction can be added at the sametime. This is the case, for example, if the contacting actuator 18 is aswivel arm.

When the vehicle connection device 14 is in its retracted position, i.e.the vehicle contact unit 16 is pulled close to the basic section 26, thebellows 22 is pushed together and the locking hooks, i.e. the firstlocking element 66 and the second locking element 68, are in engagementwith each other.

The locking elements 66, 68 thus hold the bellows 22 in its collapsedposition.

Now when the vehicle 10 is parked above a ground contact unit 12, it isintended to charge the vehicle. For this purpose, the vehicle contactunit 16 is lowered, that is, moved towards the ground contact unit 12.

First, the second locking element 68 is swiveled so that the bellows 22is released and can be inflated.

Then the compressed air source 27, i.e. here the compressor 28, isactivated and supplies compressed air to the interior space 24 of thebellows 22. The bellows 22 is inflated and stretched by the compressedair, as a result of which the vehicle contact unit 16 is moved towardsthe ground contact unit 12 in the contacting direction R_(K).

In the process, the tension elements 60 are evenly unwound from thespindle 59 so that the horizontal orientation of the base 30 of thevehicle contact unit 16 is maintained during movement as well. At thesame time, the spiral spring 61 is tensioned by the rotation of thespindle 59, so that the spiral spring 61 applies a torque to the spindle59 contrary to the unwinding direction of the tension elements 60.

The vehicle contact unit 16 is first lowered until a gap 70 has formedbetween the base 30 and the ground contact unit 12. At this point intime, the electrodes 34 do not yet touch the contact surfaces 13 of theground contact unit 12. In this position, the ground contact unit 12 isblown free.

The blowing-free process is illustrated in FIG. 5a . For blowing free,the valve 38 of the air outlet 36 is opened so that the compressed aircan escape from the interior space 24 of the bellows 22. Since the airoutlet 36 is directed into the area in front of the contacting area 32,in which the ground contact unit 12 is now located, the air stream fromthe air outlet 36 impinges on the ground contact unit 12.

It is, of course, also possible to provide a plurality of air outlets 36from which compressed air can flow out of the interior space 24 in orderto blow the ground contact unit free. It is further conceivable that theindividual air outlets 36 can be opened or closed separately or ingroups.

The air impinging on the ground contact unit 12 then flows radiallyoutwards through the gap 70 at high speed. The strong air stream alsocauses cleanable soiling such as dirt, leaves or liquid, which werelocated on the ground contact unit 12, to be transported outwards. Incase of temperatures below freezing or if there is already a layer ofsnow or ice, the heating 29 is activated so that the layer of snow orice is removed and the contacts are dried.

The steady air flow allows the ground contact unit 12 to be blown freein that area which is now opposite the contacting area 32 of the vehicleconnection device 14, so that the contact surfaces 13 in this area arefree of soiling such as dirt, leaves or liquid.

At the same time, the compressed air causes an air cushion to be formedin the gap 70, making it easier to move the vehicle contact unit 16 inrelation to the ground contact unit 12, which facilitates a lateralalignment of the vehicle contact unit 16 relative to the ground contactunit 12.

After the ground contact unit 12 has been blown free, the vehiclecontact unit 16 is lowered further, i.e. moved towards the groundcontact unit 12. In the process, air may continue to flow out of the airoutlet 36.

During the lowering process, the gap 70 decreases and the sealing lip 40and the electrodes 34 eventually come into contact with the groundcontact unit 12. The guide device 56 ensures that the vehicle contactunit 16 is parallel to the ground contact unit 12, so that it is madesure at all times that all of the electrodes 34 rest on the groundcontact unit 12.

The extended charging position of the vehicle contact unit 16 has beenreached.

In this position the sealing lip 40 closes the gap 70 in the radialdirection so that no dirt, leaves or liquid can return into the gap 70.

It is also conceivable that no sealing lip 40 is provided. In this case,a permanently increased air pressure within the gap 70 can prevent anyimpurities from returning into the gap 70.

In addition, the spindle 59 or the spiral spring 61 may be blocked sothat no tensile force acts on the tension elements 60 to pull thevehicle contact unit 16 upwards from the charging position. This allowsthe power of the compressed air source 27, in this case the compressor28, to be reduced during charging.

Then when the electrodes 34 have come into contact with the contactsurfaces 13 of the ground contact unit 12, the contact surfaces 13 arerubbed free or abraded free, as indicated in FIG. 5b , to remove anyoxide layer that may have formed on the contact surfaces 13 and/or onthe electrodes 34.

Using the sliding actuators 20, the electrodes 34 are moved in theirtransverse direction, as described with respect to FIG. 3c . Thedirection of movement, which will be referred to as the slidingdirection R_(S) below, is parallel to the front side of the base 30 andthe surface of the contact surfaces 13 and transverse to the contactingdirection R_(K). This means that the electrodes 34 are moved along thecontact surfaces 13 and thus slide over the contact surfaces 13, i.e.any oxide layer is removed, so that an electrical connection between theelectrodes 34 and the contact surfaces 13 is realized with very lowresistance.

In this way, the vehicle 10 is now electrically connected to thecharging infrastructure and can be charged.

During charging, an electrical current flows through the electrodes 34,resulting in heating of the electrodes 34 and thus in an increase in theelectrical resistance within the electrodes 34 and thermal loading ofthe electrodes 34 and the surrounding components. In order to cool theelectrodes 34, the valve 38 of the air outlet 36 may be open during theentire charging process, so that a continuous air stream flows throughthe gap 70, which cools the electrodes 34. In this way, losses duringcharging of the vehicle 10 are reduced and higher charging capacitiesare achieved.

When the vehicle 10 is fully charged or the vehicle 10 is to be moved,the vehicle contact unit 16 needs to be retracted.

To this end, the compressed air is first discharged from the interiorspace 24 of the bellows 22 and the compressed air source 27 isdeactivated, in this case the compressor 28 is switched off. Thepressure from the interior space 24 can be released by means of the airoutlet 36 and/or by a further valve (not shown) on the bellows 22.

This is followed by activation of the restoring drive 58. For thispurpose, the lock of the spindle 59 or of the spiral spring 61 isreleased, so that the spiral spring 61 applies a torque to the spindle59 contrary to the direction of rotation during unwinding. The torquecauses the spindle 59 to rotate so that a tensile force acts on thetension elements 60, pulling the tension elements 60 towards the spindle59.

If an electric motor drive 61′ of the spindle 59 is provided, thespindle 59 may of course also be driven by it or the spiral spring 61may be assisted by it.

The tension elements 60 are thereby wound up onto the spindle 59, as aresult of which the base 30 is moved evenly upwards away from the groundcontact unit 12 and the bellows 22 is pushed together. Alternatively,the operational system of the compressed air source 27 for generatingthe overpressure may also be switched over to a negative pressure modeso that it evacuates the bellows 22 and causes it to contract.

When the bellows 22 has reached its collapsed position, the two lockingelements 66, 68 lock into each other and hold the bellows 22 in thisposition.

The vehicle contact unit 16 is now securely stowed at the underbody ofthe vehicle 10, and the vehicle 10 may be moved safely.

After a detailed description above of the vehicle connection device 14with its cleaning device in the form of the air outlet 36 and/or thecompressed air source 27, it will be described in the following how thevehicle 10 or the vehicle connection device 14 is positioned relative tothe ground contact unit 12 in order to establish the electricalconnection between the vehicle connection device 14 and the groundcontact unit 12.

For this purpose, the vehicle 10 comprises a controller 72 as well as anunderbody camera 74, a front camera 76, a rear camera 78 and two sidecameras 80 (see FIG. 6), only one side camera 80 being illustrated inFIG. 6.

The controller 72 is formed by the on-board computer of the vehicle 10,which also forms the controller 72 of the vehicle connection device 14.In an alternative embodiment, separate controllers, which are preferablyin communication with each other, may be provided for the vehicle 10 andthe vehicle connection device 14.

The cameras 74, 76, 78, 80 are coupled to the controller 72 and supplyimage data that can be evaluated by the controller 72, for example todetermine the electrical contact surfaces 13 of a ground contact unit 12and/or to allow autonomous driving, even at higher speeds.

The fields of view 82 of the underbody camera 74, the front camera 76and the rear camera 78 are depicted in FIG. 6 by dotted lines and aredirected to the ground under the vehicle 10 as well as to the areas infront of and behind the vehicle 10, respectively. The fields of view ofthe side cameras 80 are directed to the areas laterally beside thevehicle 10, but are not illustrated in FIG. 6.

In the exemplary embodiment shown, the underbody camera 74 is arrangedbehind the vehicle contact unit 16, i.e. closer to the rear of thevehicle 10. The vehicle contact unit 16 here is located in the field ofview 82 of the underbody camera 74 at least in the extended loadingposition (illustrated in FIG. 6 by a dashed line), so that the underbodycamera 74 can view in particular the area which is intended to establishan electrical connection between the vehicle contact unit 16 and theground contact unit 12.

In an alternative embodiment, fewer or more cameras 74, 76, 78, 80 maybe provided for the vehicle 10 or the vehicle connection device 14.Furthermore, cameras 74, 76, 78, 80 with overlapping fields of view 82may be provided, which take images of the same area from differentperspectives. In this way, more information can be made available forevaluation, which facilitates image analyses. Moreover, the redundancyimproves functional reliability.

A lighting device 84 is mounted to the underbody of the vehicle 10between the underbody camera 74 and the vehicle contact unit 16 and isconfigured to illuminate, at least in sections, the area that is withinthe field of view of the underbody camera 74 in order to increase thepicture quality of the images taken by the underbody camera 74 and thusfacilitate an evaluation of the image data.

The lighting device 84 comprises a lamp (not shown), for example one ormore light-emitting diodes, a gas discharge lamp or a light bulb.

To protect the underbody camera 74, a protective means in the form of aprotective flap 86 is provided on the underbody of the vehicle 10. Forthis purpose, the protective flap 86 or protective cap is movablebetween a closed position and an open position. In the closed position(see FIG. 6), the protective flap 86 shields the underbody camera 74from the vehicle environment, so that in particular the lens of theunderbody camera 74 is covered and cannot be damaged by road stones orsoiled by dirt, for example. In the open position (illustrated in FIG. 6by dashed lines), the underbody camera 74 is exposed so that the fieldof view of the underbody camera 74 is essentially not obstructed by theprotective flap 86 and in particular the area can be viewed which isintended for establishing an electrical connection of the vehiclecontact unit 16 with the ground contact unit 12.

To this end, the protective flap 86 may be mounted so as to bedisplaceable or rotatable, for example, so that the protective flap 86can be displaced or swiveled to a position in front of the underbodycamera 74.

An actuator (not illustrated) is provided to move the protective means86 from the closed position to the open position.

The protective means 86 is controlled by means of the controller 72. Inparticular, it may be provided that the controller 72 is configured suchthat the protective means 86 is adjusted to the open position only whenthe underbody camera 74 is used to detect the ground contact unit 12 orthe contact surfaces 13, and remains closed in all other situations. Forexample, the underbody camera 74 may be exposed when the vehicleapproaches a ground contact unit 12 within a distance of less than 10 mand, at the same time, at a low driving speed, such as less than 10km/h. The information that the vehicle 10 is in the vicinity of a groundcontact unit 12 can be detected by the controller 72, for examplethrough wireless communication such as WLAN, Bluetooth, GPS or radio.

In addition or alternatively, it may also be provided that the driverinforms the controller 72 by means of an input that a docking maneuver,i.e. a maneuver in which an electrical connection is established betweenthe vehicle contact unit 16 and a ground contact unit 12, is to beperformed. Preferably, the controller 72 closes the protective means 86automatically when the loading process has been completed or when it isobvious that no docking maneuver is performed, for example when thedriving speed exceeds 20 km/h. In this way, it is ensured that theunderbody camera 74 is protected when it is not in use.

According to an alternative embodiment, the protective means 86 may be adiaphragm, in particular an iris diaphragm.

In the embodiment shown, the protective means 86 is provided on thevehicle 10. As an alternative, the protective means 86 may be provideddirectly on the underbody camera 74.

The controller 72 is configured such that it can carry out variousanalyses, such as, e.g., pattern recognition, using the image data ofthe cameras 74, 76, 78, 80. To this end, at least one reference image ofthe ground contact unit 12 is stored in the controller 72. Preferably,several reference images of the ground contact unit 12 are stored indifferent perspectives and in different conditions, for example with andwithout soiling (see FIG. 7). Additionally or alternatively, thecontroller 72 may comprise an image analysis software, which is providedfor evaluation of the image data of the cameras 74, 76, 78, 80.

In this way, the controller 72 can identify the ground contact unit 12of a charging infrastructure and detect the electrical contact surfaces13 of the ground contact unit 12 as well as an insulation surface 88(see FIG. 7), which surrounds the electrical contact surfaces 13 andelectrically insulates them from each other.

Furthermore, the controller 72 can determine which contact surfaces 13are exposed and are thus directly suitable for establishing anelectrical connection.

The controller 72 can further determine which contact surfaces 13 arenot exposed and are therefore not directly suitable for establishing anelectrical connection. Non-exposed contact surfaces 13 are distinguishedin particular by the fact that they are at least partially covered, forexample because the contact surface 13 is dirty or concealed by anobject. Here the controller 72 is able to distinguish between cleanablesoiling, such as water puddles 90 or loose chippings, and non-cleanablesoiling, such as larger stones 91 with a volume of several cm³ or ablock of wood 93. Cleanable soiling here involves exclusively soilingwhich can be removed using the cleaning device of the vehicle connectiondevice 14, i.e. in particular by blowing free.

The controller 72 is also able to identify contact surfaces 13 that aredamaged or completely missing, and can classify them as non-cleanablesoiling and treat them as such.

In order to establish an electrical connection between the vehiclecontact unit 16 and the ground contact unit 12, which is suitable forcharging the battery of the vehicle 10, a group or combination of threeexposed contact surfaces 13 is required, each contact surface 13adjoining each of the other two contact surfaces 13, so that a kind oftriangle is described. In FIG. 8, the area 92 has at least one suchgroup or combination, while the area 94 does not contain such a group.

In an alternative embodiment, both the number and the positions of theexposed contact surfaces 13 of the group that is required to establishan electrical connection may differ. In particular, according to oneembodiment, only two exposed contact surfaces 13 may be requiredtherefor.

Optionally, when checking the exposed or cleanable contact surfaces,only those sections of the ground contact unit are taken intoconsideration which can actually be reached by the vehicle contact unit16.

After the controller 72 has identified the exposed contact surfaces 13,it can select an area 92 of the ground contact unit 12 that is to beheaded for to establish the electrical connection. The area 92 may belarger than the required group of exposed contact surfaces 13 in orderto take the dimensions of the vehicle contact unit 16 into account andto ensure in this way that the entire vehicle contact unit 16 rests onthe ground contact unit 12 in parallel contact.

When selecting the area of the ground contact unit 12 that is to beheaded for to establish the electrical connection, the controller 72 canalso incorporate non-exposed but cleanable contact surfaces 13, i.e. thearea may comprise one or more non-exposed but cleanable contact surfaces13. In this case, a cleaning step is performed to expose the contactsurface 13.

A cleaning step may also be performed if no soiling was detected, i.e.when the controller 72 classifies all contact surfaces 13 in the area tobe contacted as being exposed. In this way, any undetected cleanablesoiling can be removed, as a result of which the quality of theelectrical connection can be increased.

Without having to move the vehicle 10, after each cleaning step theresult of the cleaning can be checked by determining the condition ofthe contact surfaces 13 by means of the underbody camera 74.

After each cleaning step, the result of the cleaning can be checked bydetermining the condition of the contact surfaces 13 by means of theunderbody camera 74, without having to move the vehicle 10.

The controller 72 further provides a positioning aid which assists thedriver in positioning the vehicle 10 or the vehicle connection device 14relative to the ground contact unit 12, or autonomously steers thevehicle 10 to this position, in which an electrical connection of thevehicle contact unit 16 to the ground contact unit 12 can beestablished. In particular, this function serves to head for the area 92which is to be approached for establishing the electrical connection.When the positioning aid assists the driver, the controller 72 providesoptical signals, such as direction indications, to the driver fororientation via a display device, for example a display.

In order to be able to determine the relative position of the vehicle 10in relation to the ground contact unit 12 or the individual contactsurfaces 13 more precisely, the ground contact unit 12 may have variousfeatures provided thereon (see FIG. 8). The features may also facilitatethe detection of the ground contact unit 12 or the individual contactsurfaces 13 and/or may provide additional information, for example theidentification number of the ground contact unit 12.

In FIG. 8, the following features are provided on the ground contactunit 12: a QR code 96, various binary bar codes or lines 97, 98, 99,110, a pattern 101 of equidistant dots arranged around individualcontact surfaces 13, three triangular symbols 102, the middle one ofwhich is aligned with the middle of the ground contact unit 12,arrow-shaped markings 103 which emphasize the contours of individualcontact surfaces 13, and a contact surface 104 which distinguishesitself by a contrast that is different from that of the other contactsurfaces 13, for example due to a particular coloring. Furthermore, thecontact surfaces 13 may form one or more features by their shapes,orientations and/or arrangements.

The positioning aid can provide the positioning of the vehicle 10relative to the ground contact unit 12 or the individual contactsurfaces 13 with an accuracy of ±40 mm, more particularly ±10 mm, bymeans of the features and when a high resolution camera 74, 76, 78, 80,in particular the underbody camera 74, is used.

In addition or alternatively, features may be provided at a close rangeof approx. 3 m from the ground contact unit 12, which make it easier forthe controller 72 to determine the position or orientation of thevehicle 10 or allow conclusions to be drawn about the presence of aground contact unit 12, even if it has not (yet) been directly detected,for example because it is covered by a layer of leaves or snow.

FIG. 9 shows a parking space 106 having a ground contact unit 12 andwhich is intended as a parking spot for the vehicle 10 during thecharging process.

The parking space 106 has a boundary 108 in the form of a marking on theground, which is formed by a border formed of three parallel lines. Thefact that the distance between the lines decreases toward the middle ofthe parking space 106 indicates on which side of the boundary 108 theground contact unit 12 of the parking space 106 is located.

Transmitters 110 are provided at two of the corners of the parking space106 and provide an electromagnetic signal which can be utilized by thecontroller 72 for orientation.

A plurality of lines 112 extending from the ground contact unit 12 areprovided within the boundary 108, which run parallel to an edge of theground contact unit 12. The distance of the lines 112 relative to eachother increases as the distance from the ground contact unit 12increases, so that the distance between the lines 112 can be used as anindicator for the distance from the ground contact unit 12.

The above-mentioned features are stored as a reference in the controller72 and can thereby be recognized and interpreted by the controller 72.

In summary, the procedure for establishing an electrical connection ofthe vehicle contact unit 16 to a ground contact unit 12 of an electriccharging infrastructure is outlined below.

In the exemplary embodiment shown, the vehicle 10 approaches a groundcontact unit 12, the spatial proximity of which is detected by the GPSposition stored in a map or by receiving the wireless communicationsignal, such as WLAN, Bluetooth or radio. Within close range of theground contact unit 12, the vehicle 10 reduces its speed to less than 10km/h and exposes the underbody camera 74 in that the optional protectivemeans 86 is opened. The cameras 74, 76, 78, 80 are used to determine theposition and orientation of the ground contact unit 12. Here, thecontroller 72 makes use of the features at the parking space 106 and atthe ground contact unit 12 for orientation. After the ground contactunit 12 has been detected, the controller 72 uses the image data of thecameras 74, 76, 78, 80 to determine which contact surfaces 13 aresuitable for establishing an electrical connection. Now the vehicleautonomously steers towards the area with the selected group of contactsurfaces 13 or assists the driver in doing so. When the position isreached in which the vehicle contact unit 16 is located vertically abovethe selected area, the vehicle contact unit 16 is lowered and a cleaningstep is performed to remove soiling and improve the quality of theelectrical connection.

If heavy soiling was detected in the selected area, the vehicle contactunit 16 is subsequently raised again and the cleaning result is checkedusing the underbody camera 74. Depending on the degree of soiling,further cleaning steps may now follow to expose the contact surfaces 13.Alternatively, it is also possible to approach a different area on theground contact unit 12. This can be effected either by moving thevehicle contact unit 16 also laterally and/or by moving the vehicleautonomously.

When the area has been cleaned or if no soiling was detected in theselected area, the vehicle contact unit 16 is moved downward against theground contact unit 12 and, optionally, a cleaning step is carried out.When the contact between the electrodes 34 and the contact surfaces 13has been established, the contacted contact surfaces 13 are connectedand the process of charging the vehicle battery begins. During thecharging process, the ground contact unit 12 is monitored by means ofthe underbody camera 74 in order to initiate a protective reaction, forexample if an animal approaches the vehicle contact unit 16. When thecharging process is completed or is to be discontinued, the contactedcontact surfaces 13 are disconnected again and the vehicle contact unit16 is retracted. Finally, the protective means 86 is closed in order toshield the underbody camera 74, and the vehicle 10 is ready to continueits journey.

In this way, an electrical connection of the vehicle contact unit 16 tothe ground contact unit 12 of the charging infrastructure can beprovided with high quality and low losses.

The embodiments described should only be regarded as exemplary versions.The features described may, of course, be combined with each other asdesired.

The invention claimed is:
 1. A method for establishing an electricalconnection of a vehicle contact unit of a vehicle which is at least inpart electrically powered, to a ground contact unit of an electriccharging infrastructure which has a plurality of electrical contactsurfaces, at least two of which have to be contacted by the vehiclecontact unit for charging a vehicle battery, wherein the methodcomprises the step of: a) detecting at least one of the electricalcontact surfaces and at least one insulation surface surrounding theelectrical contact surfaces with aid of at least one camera on thevehicle, for establishing an electrical connection.
 2. The methodaccording to claim 1, wherein the method comprises the step of: b)determining, with the aid of at least one camera on the vehicle, atleast one of which contact surfaces of the ground contact unit aresuitable for the electrical connection and whether a soiling of theground contact unit is opposed to a safe charging process.
 3. The methodaccording to claim 2, wherein in step b) it is determined, with the aidof the at least one camera on the vehicle, which contact surfaces forthe electrical connection are exposed.
 4. The method according to claim2, wherein in step b) it is determined, with the aid of the at least onecamera on the vehicle, which contact surfaces for the electricalconnection are not exposed and show a soiling.
 5. The method accordingto claim 4, wherein in step b) it is determined which contact surfacesfor the electrical connection show a soiling is cleanable.
 6. The methodaccording to claim 2, wherein the method comprises the step of: c)selecting an area of the ground contact unit that is to be headed forelectrical connection, the area including a group of exposed contactsurfaces by means of which the electrical connection can be established.7. The method according to claim 2, wherein an at least one of anunderbody camera, a front and a rear camera of the vehicle is used toperform at least one of step a) and step b).
 8. The method according toclaim 1, wherein the method comprises the step of: d) selecting an areaof the ground contact unit that is to be headed for electricalconnection, the area including at least one contact surface which is notexposed for establishing an electrical connection.
 9. The methodaccording to claim 8, wherein after selecting the area, the vehiclecontact unit is moved downward against the ground contact unit toestablish the electrical connection.
 10. The method according to claim1, wherein the method comprises the step of: e) performing a cleaningstep.
 11. The method according to claim 10, wherein subsequently afterthe cleaning step, a step b) is performed comprising determining, withthe aid of at least one camera on the vehicle, at least one of whichcontact surfaces of the ground contact unit are suitable for theelectrical connection and whether a soiling of the ground contact unitis opposed to a safe charging process.
 12. The method according to claim1, wherein after selecting an area of the ground contact unit that is tobe headed for electrical connection, the area including at least onecontact surface, the vehicle is moved, steering automatically, oroptical steering signals are output in an interior for a driver formanual steering of the vehicle in order to place the vehicle contactunit in a position in which it can be coupled to the selected contactsurfaces.
 13. A vehicle connection device for electrically connecting avehicle contact unit of a vehicle which is at least in part electricallypowered, to a ground contact unit of an electric charging infrastructurewhich has a plurality of electrical contact surfaces, at least two ofwhich have to be contacted by the vehicle contact unit for charging avehicle battery, comprising the vehicle contact unit, at least onecamera and a controller coupled to the camera, wherein the controller isconfigured such that it can determine exposed electrical contactsurfaces of the ground contact unit by means of the at least one camera.14. The vehicle connection device according to claim 13, wherein thevehicle connection device comprises a cleaning device, which is providedfor exposing the electrical contact surfaces of the ground contact unitat least in a selected area.
 15. The vehicle connection device accordingto claim 13, wherein the controller for a positioning aid is configuredsuch that it can detect visual features on the ground contact unit whichare stored as a reference in the controller.
 16. The vehicle connectiondevice according to claim 15, wherein the electrical contact surfaces ofthe ground contact unit constitute a visual feature for the positioningaid.